Is there any way to change viewport preview pass through script?
Developer Extras
Relying on the info area to write scripts is IMO not the way to go.
Some posts explaining how to find what the property is.
Changing the shading type in Python
Blender python : How to set object appearance in viewport?
With developer extras turned on mousing over the property

Telling us the type and its property of interest View3DShading.render_pass  For a 3D viewport, will find any property setting belongs to the space.   Scrolling to References at bottom of page confirms this ie SpaceView3D.shading is an instance of View3DShading
To the python console:
&gt;&gt;&gt; for i, a in enumerate(C.screen.areas):
...     i, a.type
...     
(0, 'PROPERTIES')
(1, 'CONSOLE')
(2, 'VIEW_3D')
(3, 'TEXT_EDITOR')

Area 2 is a view 3d, its active space
&gt;&gt;&gt; space = C.screen.areas[2].spaces.active

The render pass property of shading group
&gt;&gt;&gt; space.shading.render_pass
'COMBINED'

Set to something else.
&gt;&gt;&gt; space.shading.render_pass = 'MIST'
&gt;&gt;&gt; 

Note in a script to run from the context of a view3d, then use
space = context.space_data